There's nothing you can do but buy a new game...
If this is for CoD4 or CoD5, then your CD-Key might have been stolen by malware/keyloggers, that is/are installed on your PC. Run some checks... and if you really want to be sure, format your hard drive....
If the violation happened on a server, which does not stream to any AC organisation (PBB, PsB, GV, AON etcetc), then you just can't find any info on those violations....